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Midterm

BIOB32H3 Study Guide - Midterm Guide: Purkinje Fibers, Ammonia, Active Transport


Department
Biological Sciences
Course Code
BIOB32H3
Professor
Kenneth Lam
Study Guide
Midterm

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B32
LEc 6
what's the meaning of 60Hz
Nernst equation for one single ion
Goldman equation for multiple ion ( na= and K+_ )
lec 5
bulk flow =convective transport
the sequence for blood flow in bony fish heart
--sinus venous( the veins are where the input of blood is) , and then atrium, and
then ventricle, and then bulbus arteriousu
where the pacemaker located for the fish and vertebrate animals?
-sinous venous
-sinoatrail node
what are the two types of conduction fibres
internodal pathway and purkinje fibres
sequece of AP conduction : first internal pathway, then AC node, then AV bundle
(bundle of his) then purkinje fibres
what are the method to upregulate and downregulate the heart rate?--by
intervention from nerves
-note that it's not direcly acting upon changing the movement of ions, but by
acting on the mscarinic receptor or the G protein, which then control the
movement of the ion through the ion channels, --so they( the receptors receiving
the NT) are not ionic channels
--sympathetic regulatoin
-neuron secrete NE, or neurone ask the adrenal medulla to secrete E
-then beta, G protein and then adnylyl cyclase( know how to spell them) !!!
-rate of de is increased + frequency of AP increase( more frequent AP,
faster HR)
--para: to decrease HR
-para neuron secrete Ach
-muscarinic receptor ( not direcly control the movement of ion, so similar to
beta receipr and G protein )
-wich then act on G protein
-which act on the K+ and Ca++ channels

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--what kind of effect may b seen here?
-to resist the further depolarization
--slowing the slope
==time for depolarization is longer
==increasing the distance between the potentials so less frequency of AP
--increase time for depolarization
-decrease frequency of AP
-so both involve the Ca2+ channel
but in anthropoid heart, which is neurogenic
--you see the Ach to increase HR ,while in human heart, Ach is to decrease HR
if i give you bath two types of heart ( my heart and antropod heart) into Ach-bathed solution, then
you expec tto see opposite heart rate change
lec 4
the bird 's air sac's function
--to disassociate the movement in the mouth and trachea ( deadspace) with the foliation of the
lungs, so that the lungs can still do gas exchange without fresh air getting into the bronchi
birds and fish do counter-current in respiration --in parabronchin
huma do concurrent respiration -in alveolar and bronchi
macula densa : distal tubule
granular cells( aka the juxtamedullary cells: release renin )
-function of renin -
——renin secretion from baroreceptor from Juxtameddularry cells
trigggered by which two factors ( medulla gada and macula densa )
what are the factors affecting ultrafiltratoin?
-net hydrostatic pressure diff—that’s why when your body sense a drop in BP, or a decrase
in GFR , renin will be released from juxtamedullary cells ( this is triggered by the the medulla
obligada receptor, and the macula dnesa cells in the distal tubule)
-colloid osmotic pressure of blood( attraction by protein in the blood)
-hydraulic permeability along capillary
urine formation
1 as you go down the luman, you see increasing conc in the interstitial fluid
-for what?--to make sure water is reabsorbing by osmosis from the lumen into the
interstitial fluid( recall that the ADH increase the water reabsorption by inserting more aquaprins
into the distal tubule and collecting duct; while the antiogensin II act the AC to secrete
aldesterone to increase the reabsoprtion of na+ into the interstitial fluid and hence water follows
after
-why?the increasing concentration in the interstitial fluid is maintained by the desceinding
and ascending loop of Henleby actively pumping ions( active transport of NaCl into the
interstitial fluid ) and passive diffusion of the NaCl into the interstitial fluid
--in the upper portion, this pumping of ion is done by active transport of Nacl, and the
lower you go, the more it pumps
--in the lower por of the loop of Henle, this is done by passive diffusion of NaCl
--after the interstitial fluid concentration is build up as you down the Loop of Henlel,

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you are also building up the increasing interstitial fluid concentration/osmolarity for the CT
--you use CT to reabsorb water back to the blood, to maintain blood pressure
--but the problem is when you go down the CT,almost at the bottom of the
tubule, you want to give a push in the water reabsorption, by what ? by the passive diffusion of
urea from the lumen into the intersitital fluid, which can contribute to the increasing osmolarity in
the interstitial fuild ( counter-intuitive at first sight, since you want to get rid of the urea in the
urine, but now you are reabsorbing it back to the blood )
2
renal corpuscle, ( B and gloomier) : ultrafiltrate the glucose and AA from blood into the lumen ,
but most (100%)of which is reabsorbed back in the next step
prox. tubule: site of glucose and AA reabsorption
dist, and CT: filtrate K+, H+ and NH3(buffer) into kidney lumen --that's why human and birds have
slightly acidic urine
: reabsorb Na+ and Cl- and HCO3- into interstitial fluid and then to the blood ,
but Cl- wll stay inside the interstitial fluid
glucose reabsorption -3 method
your blood have mostly HCO3-, and almost no H+( H+ is secreted into the kidney lumen and as
urine)
-so H+ excretion into urine , and HCO3- reabsorption all the time
-how?
CO2( diffuse from the blood into the interstitial fluid) 's CA (carbonic anhydrase) reaction to make
H+and HCO3-
--slide to pump H+ into lumen, and HCO3 reabsorb back to blood
how to make sure H+ keeps going into the lumen, even when there's lots of H+ already in the
lumen? --note that H+ pump stops when urine pH is lower than 4.5, so how does it keeps on
pumping h+ into the lumen?
-by buffering chemical: ammonia ( NH3) from the blood by diffusion, or phosphate (
HPO42-) by filtration in the Renal corpuscle
-ammonia is a breakdown product of protein, so if you eat lots of protein, then you'll have
acidic urine
-cause too much buffer ( NH3) in the blood from SI, and then in the lumen
how does renin -angiotensin system work , and how does anti-diuretic hormone work?
what happens when your BP is dropping /when you are loosing water?
-increased renin( sensed by tge two mechnisma; one is medulla obbligada sensing the BP,
and the other is distal tubule’s macula densa cell sensing blood flow rate) , and all the
downstream enzymes( antiogensin I, II), aldosterone from AC( in charge of Na+ reabsorption),
-and increase ADH ( in charge of H20 reabsorption by permeability control)by inserting
auaporins in CT triggered by two sources ( low BP, and high osmolarity) sensed by the
hypothalamic neurons
ADH=vassopression =anti-diuretic hormone ( reserve water, instead of pee it out)
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